Independent comparisons. We may earn from shop links. More info

How to use an impact driver

Updated: 22 October 2026

You are at a fence rail, trying not to chew the screw head. How to use an impact driver is a short sequence: fit an impact-rated 6.35 mm hex bit, lock it in the collet, start slowly in line with the screw, and ease off as the head meets the timber. The four cordless bodies on the [impact driver comparison](/hub/tools/impact-driver) do not list a clutch, so the trigger is the only stop. Peter F., DIY & tools editor, based this page on amazon.co.uk listings and UK sources checked on 21 October 2026, with no lab test. A qualifying purchase can earn a commission at no extra cost to you.

You are at a fence rail, trying not to chew the screw head.

Our top picks

DeWalt DeWalt DCF887N

Best overall

DeWalt DeWalt DCF887N
9.4/10about £59.95
View offer
Einhell Einhell TE-CI 18/1 Li

Alternative

Einhell Einhell TE-CI 18/1 Li
9.2/10about £50.39
View offer
Galax Pro Galax Pro 95307

Best value

Galax Pro Galax Pro 95307
8.8/10about £42.83
View offer
On this page
  1. 1.Fit an impact-rated hex bit
  2. 2.Seat the bit in the collet
  3. 3.Drive the screw and stop at flush
  4. 4.When to put the driver down

Fit an impact-rated hex bit

The nose takes a 6.35 mm hex shank. A round drill bit, an SDS bit and a hole-saw arbor will not lock, so this tool will not bore the pilot. Screwfix says impact-rated bits are required and that a normal bit is likely to shatter. A mixed set there starts at about £9.99. PZ2 suits most UK wood screws. If it climbs out, move to Torx or a hex-head screw. Galax Pro includes six bits listed as screwdriver bits, and one reviewer called the fit odd, so do not treat them as impact-rated. Bit cost is on the impact driver buying guide.

Seat the bit in the collet

The collet is a spring sleeve, not a keyed drill chuck. On the Galax Pro listing you pull the collet back, push in the 6.35 mm hex, and let the sleeve return. Do not copy that motion onto the DeWalt, the Einhell or the Bosch. Those listings do not describe the sleeve. Einhell states a hexagon socket, DeWalt states 6.35 mm, and Bosch does not state a chuck size. Use the manual for the body you are holding. Push the shank in until it stops, then tug it. If it comes out, it never locked. Side-to-side play in the DeWalt collet is a repeated UK review complaint. One Einhell reviewer said the collet would not hold a bit at all. That is a return, not a cue to force a round shank.
DeWalt DeWalt DCF887N

Testsieger

DeWalt DeWalt DCF887N
9.4/10about £59.95
View offer

Drive the screw and stop at flush

Keep the bit in the recess and the tool in line with the screw. A tilt walks out of a Pozidriv head. Start on a light trigger, and ease off as the head reaches flush. Holding on after that sinks the head and tears decking timber. The DeWalt has three speeds, and UK reviewers describe a wide gap between setting 1 and setting 2. Move up only once the screw is running true. Galax Pro and Einhell have a variable trigger and no speed switch. Bosch lists two settings. A hinge screw should not start on this tool.

When to put the driver down

A small or soft screw belongs on a combi drill, which has a clutch these drivers do not. Hardwood near the end of a board needs a pilot from a drill. The split is on impact driver vs combi drill. Wheel nuts need a square-drive wrench. The Bosch title says wrench, but reviews talk about screws at a stated 210 Nm. Read impact driver vs impact wrench before you trust the title. Call a professional for a specified structural torque, for wheel nuts, and for a workplace vibration assessment. These listings give no vibration figure, so there is no safe running time to quote.

Common questions

What shank fits an impact driver, and what will not go in?
A 6.35 mm hex shank is what the collet takes, and Screwfix says it should be impact-rated. Round drill bits, SDS bits and hole-saw arbors do not fit. The six Galax Pro bits are listed as screwdriver bits, so the box is not proof they are impact bits.
How do you start a screw without cam-out?
Seat the bit in the recess and keep the driver in line. Pull the trigger only until the thread bites. A tilt makes a cross-head throw the bit. PZ2 suits most UK wood screws. If it still cams out, switch to Torx rather than squeezing harder.
Why is there no numbered clutch, and when should you ease off?
None of these four lists a numbered clutch. The anvil keeps striking while the trigger is held, so ease off as the head reaches flush, before it sinks into the timber. On a trigger-only tool, your hand is the only stop.
What does Screwfix say happens with a normal screwdriver bit?
Screwfix says a normal bit is likely to shatter under the rotational blows, so wear eye protection and buy impact-rated bits. A mixed set there starts at about £9.99. These listings give no decibel figure, and HSE time bands are not a measured safe time for these bodies.
Should you use a PZ2 bit or a Torx bit?
Start with PZ2 for a Pozidriv wood screw, the usual fence and decking head in the UK. Move to Torx, or a hex-head screw, when the cross-head cams out. Leave household bits for a drill that has a clutch.
When should you use a combi drill instead?
Use a combi for pilot holes, for masonry, and for a small screw that a clutch can stop. This driver will overdrive a hinge screw, and it cannot hold a round-shank bit. A specified structural torque is a job for a professional, not a higher setting.

Related pages

Best impact driver

Impact driver

Impact driver buying guide: nose, battery and torque

Impact driver vs combi drill: which tool to buy first

Impact driver vs impact wrench: hex bit or square socket

Sources

Public UK sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the four amazon.co.uk listings captured on 21 October 2026. Vibration limits apply at work. They are not a measurement of these drivers.

  1. Screwfix, Impact driver buying guide (retrieved 21 October 2026)
  2. Screwfix, 18 V impact drivers (retrieved 21 October 2026)
  3. HSE, Hand-arm vibration regulations (retrieved 21 October 2026)
  4. legislation.gov.uk, Vibration regulation 4 (retrieved 21 October 2026)
  5. HSE, Construction vibration FAQ (retrieved 21 October 2026)
  6. GOV.UK, Supply of Machinery (Safety) Regulations 2008 (retrieved 21 October 2026)
  7. OPSS, Product safety report 2511-0084 (retrieved 21 October 2026)
  8. Homebuilding, Impact driver vs impact wrench (retrieved 21 October 2026)